Etymologies

Examples

The late Carl Sagan, a charismatic champion of searching for extraterrestrial signals in the 1980s, envisaged an advanced alien civilization deliberately beaming narrow-band radio messages at Earth to attract our attention.

To see if this is true, they try to think of what life as we know it might do to make their presence known, and they've decided that we would send signals out into space that were different from all of the other signals out there (narrow-band EM transmissions).